Compressor and vacuum machine

ABSTRACT

A compressor includes: a cylinder; a piston arranged within the cylinder; an outer rotor type motor causing the piston to reciprocate within the cylinder; and a fan fixed to a rotor of an outer rotor type motor and facing at least a part of the cylinder.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2012-011348, filed on Jan. 23, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND

(i) Technical Field

The present invention relates to a compressor and a vacuum machine.

(ii) Related Art

There is known a compressor and a vacuum machine which compress and discharge intake air by a piston which reciprocates within a cylinder by a motor. Japanese Patent Application Publication No. 2004-183498 discloses such a compressor.

For example, the piston slides on an inner surface of the cylinder, so that the piston and the cylinder might heat up. Also, for example, air is adiabatically compressed within the cylinder, so that the temperature of the adiabatically compressed air becomes high. In a case where the compressor or the vacuum machine is continuously used while heating up in such a way, for example, the piston wears to adversely influence parts, the compressor itself, or the vacuum machine itself.

In Japanese Patent Application Publication No. 2004-183498, a fan for cooling the compressor is arranged in an axial direction of a motor. However, there is a problem with the high height in the axial direction. Further, in Japanese Patent Application Publication No. 2004-183498, an inner rotor type motor is used. Thus, there is another problem that the inner rotor type motor has a torque smaller than that of an outer rotor type motor having the same size as the inner rotor type motor.

SUMMARY

It is therefore an object of the present invention to provide a compressor and a vacuum machine, thereby suppressing heating, reducing thickness, ensuring torque, and making a compression state or a vacuum state more effectively.

According to an aspect of the present invention, there is provided a compressor includes: a cylinder; a piston arranged within the cylinder; an outer rotor type motor causing the piston to reciprocate within the cylinder; and a fan fixed to a rotor of an outer rotor type motor and facing at least a part of the cylinder.

According to another aspect of the present invention, there is provided a vacuum machine includes: a cylinder; a piston arranged within the cylinder; an outer rotor type motor causing the piston to reciprocate within the cylinder; and a fan fixed to a rotor of an outer rotor type motor and facing at least a part of the cylinder.

Therefore, the fan can cool the cylinder, thereby suppressing the compressor and the vacuum machine from heating. Also, the fan faces at least a part of the cylinder, thereby reducing the thickness of the compressor and the vacuum machine. Further, the outer rotor type motor can ensure the torque, so the compression state or the vacuum state can be made more effectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a compressor;

FIG. 2 is an external view of the compressor;

FIG. 3 is a view of an inner structure of a motor;

FIG. 4 is a view of inner structures of a cylinder;

FIGS. 5A and 5B are graphs of experimental results illustrating effects of a reduction in a driving noise by a fan; and

FIGS. 6A and 6B are graphs of experimental results illustrating effects of a reduction in the driving noise by the fan.

DETAILED DESCRIPTION

A compressor A will be described as the present embodiment Additionally, a vacuum machine has the same structure as the compressor A. FIGS. 1 and 2 are external views of the compressor A. The compressor A includes: four cylinders 10; a crankcase 20 attached with the four cylinders 10; a motor M arranged at the upper side of the crankcase 20; and a fan F attached with the motor M. The fan F faces at least a part of the cylinder 10. The fan F is attached with the motor M, and the fan F rotates in accordance with the rotation of the motor M. The rotation of the fan F can cool the four cylinders 10 and the crankcase 20. The piston 25 as will be described later reciprocates within the cylinder 10. The cylinder 10 and the crankcase 20 are made of aluminum having a good heat radiation characteristic.

FIG. 3 is a view of an internal structure of the motor M. The motor M includes: coils 30, a rotor 40, a stator 50, and a printed circuit board PB. The stator 50 is made of metal. The stator 50 is secured by a non-illustrated support member. The plural coils 30 are wound around the stator 50. The coils 30 are electrically connected with the printed circuit board PB. As for the printed circuit board PB, conductive patterns are formed on an insulating board having rigidity. A power supply connector E for supplying power to the coils 30 is mounted on the printed circuit board PB. Also, a signal connector C and a non-illustrated electronic parts are mounted on the printed circuit board PB. For example, the electronic part is an output transistor (a switching element) such as an FET for controlling an energized state of the coils 30, or a capacitor. The coils 30 are energized, so the stator 50 is energized.

The rotor 40 includes: a rotational shaft 42; a yoke 44; and plural permanent magnets 46. The rotational shaft 42 is rotationally supported by non-illustrated bearings arranged within the crankcase 20. The yoke 44 is secured to the rotational shaft 42 through a hub 43, so the yoke 44 rotates together with the rotational shaft 42. The yoke 44 has a substantially cylindrical shape and is made of metal. The plural permanent magnets 46 are secured to the inner circumferential side of the yoke 44. The permanent magnets 46 face the outer circumferential surface of the stator 50. The coils 30 are energized, so the stator 50 is energized. Thus, the magnetic attractive force and the magnetic repulsive force are generated between the permanent magnets 46 and the stator 50. The magnetic force allows the rotor 40 to rotate with respect to the stator 50. As mentioned above, the motor M is an outer rotor type motor in which the rotor 40 rotates.

The fan F includes: a body portion FM having a substantially cylindrical shape; plural blade portions FB formed at the radial outside of the body portion FM. The body portion FM of the fan F is secured to the yoke 44 of the rotor 40 by, for example, press fitting, an adhesive bond, or screwing to the hub 43 with the rotor 40. Specifically, the inner diameter of the body member FM fits the outer diameter of the yoke 44. The Fan F is made of resin.

As illustrated in FIG. 3, the fan F and the motor M are arranged in the radial direction of the fan F when viewed from the cross section including the axis of the motor M. Specifically, the fan F, the coils 30, the rotor 40, and the stator 50 are arranged in the radial direction of the fan F. Thus, for example, as compared with a case where the fan F is arranged at the front side in the axial direction (the left side in FIG. 3) and is secured to the front end of the rotational shaft, the compressor A according to the present embodiment has a reduced thickness in the axial direction. Further, the fan F is close to the cylinders 10, thereby improving the cooling effects.

Also, in a case where the fan F is arranged at the front side of the motor M in the axial direction and is secured to the front end of the rotational shaft, the rotational shaft has to be long. If the rotational shaft is long, it is necessary to provide a large bearing or plural bearings in order to support the rotation of the rotational shaft. In the compressor A according to the present embodiment, the short rotational shaft 42 is employed, thereby supporting the rotational shaft 42 by a small bearing or few bearings. Therefore, the whole weight of the compressor A is reduced.

FIG. 4 is a view of the inner structure of the cylinder 10. The cylinder 10 includes: a cylinder body 12; a cylinder head 15 connected to the front side of the cylinder body 12. A chamber 13 is formed in the cylinder body 12. The chamber 13 is defined by the space, which is formed within the cylinder body 12, and the distal end of the piston 25, which reciprocates within the space. The piston 25 reciprocates in response to the rotation of the motor M, so the capacity of the chamber 13 increases or decreases. The proximal end of the piston 25 is located within the crankcase 20 and is coupled to the rotational shaft 42 of the motor M through a non-illustrated bearing. Specifically, the proximal end of the piston 25 is eccentric to the center of the rotational shaft 42, and the piston 25 reciprocates in response to the rotation of the rotational shaft 42 in the single direction. The phase difference between the four pistons 25 arranged within the four cylinders 10 is 90 degrees.

The cylinder head 15 is formed with: an inlet port 16; and an intake chamber 17 communicated with the inlet port 16 and the chamber 13. Also, the cylinder head 15 is formed with: an exhaust port 19; and an exhaust chamber 18 communicated with the exhaust port 19 and the chamber 13. The reciprocation of the piston 25 changes the capacity of the chamber 13. In response to this, air is introduced to the chamber 13 through the inlet port 16 and the intake chamber 17 and is compressed within the chamber 13. The compressed air is discharged through the exhaust chamber 18 and the exhaust port 19. Each of the intake port 16 and the exhaust port 19 is attached with, for example, a tube.

A valve member V is provided for opening and closing a hole H through which the intake chamber 17 is communicated with the chamber 13. Likewise, a valve member is provided for opening and closing a non-illustrated hole through which the exhaust chamber 18 is communicated with the chamber 13. The valve member V is made of, for example, an elastic material. When the piston 25 reciprocates, the valve member V permits air to be introduced from the intake chamber 17 to the chamber 13 and restricts air from flowing backward from the chamber 13 to the intake chamber 17. Also, the non-illustrated valve member permits air to be discharged from the chamber 13 to the exhaust chamber 18 and restricts air from being introduced from the exhaust chamber 18 to the chamber 13.

Specifically, while the capacity of the chamber 13 is being increased by the piston 25, the valve member V opens the hole H, and air is introduced to the chamber 13 through the intake port 16 and the intake chamber 17. While the capacity of the chamber 13 is being decreased by the piston 25, the valve member V closes the hole H through which the chamber 13 is communicated with the intake chamber 17, and the non-illustrated valve member opens a hole through which the chamber 13 is communicated with the exhaust chamber 18, so the compressed air is discharged outside through the exhaust chamber 18 and the exhaust port 19.

A lip seal 27 having a ring shape is provided at the distal end of the piston 25. The lip seal 27 slides on the inner wall of the cylinder body 12 in response to the reciprocation of the piston 25. The lip seal 27 prevents air from leaking through a gap between the distal end of the piston 25 and the inner wall of the cylinder body 12. The lip seal 27 is made of resin.

Thus, the lip seal 27 of the piston 25 slides on the inner wall of the cylinder body 12, so that the cylinder body 12 and the piston 25 heat. Also, air is adiabatically compressed within the chamber 13, so that the temperature of the air within the chamber 13 becomes high. When such a high temperature state is kept, the life of the lip seal 27 or another part might deteriorate. In the compressor A according to the present embodiment, the fan F is secured to the motor M so as to face the cylinder 10. Specifically, the fan F is provided to face the chamber 13 within the cylinder 10. Additionally, it is preferable that the fan F should face the cylinder head 15. Thus, the fan F sends air toward the cylinder 10 in response to the rotation of the motor M. This promotes cooling of the cylinder 10. Accordingly, this can suppress the life of parts from deteriorating.

Also, the fan F is secured to the rotor 40, so the fan F is arranged close to the cylinders 10. Therefore, the cylinders 10 can be effectively cooled.

The air directly or indirectly flows toward the crankcase 20 and the motor M from the fan F. This can also cool the crankcase 20 and the motor M. The cooling of the crankcase 20 can suppress the wear between parts of the rotational shaft 42 and the piston 25 coupled with each other within the crankcase 20, and can suppress the wear of the bearing, arranged within the crankcase 20, of the rotational shaft 42. Also, the motor M itself is cooled to suppress heat from transferring to the cylinder 10 and the crankcase 20. Thus, the whole compressor A can be cooled.

Therefore, the fan F can cool the cylinder 10, the crankcase 20, and the motor M. Thus, it is not necessary to provide fans respectively cooling these parts, unlike a device using a conventional compressor or a conventional vacuum machine. Thus, as for the device using the compressor according to the present embodiment, the number of the parts is reduced and the manufacturing cost is reduced.

Also, in view of the compression efficiency of air, low temperature air is introduced and compressed, so the large amount of air can be introduced into the chamber 13. The fan F is arranged to face the chamber 13, thereby cooling the air within the chamber 13 and the portion around the chamber 13. Thus, a high temperature air is suppressed from being introduced into the chamber 13. Thus, air can be introduced into the chamber 13 and can be compressed efficiently.

Also, the motor M according to the present embodiment is the outer rotor type motor. Unlike an inner rotor type motor, the rotor is made of a metal plate having a thin and a large size. Thus, the metal plate might vibrate to make a driving noise in rotating, so it might be necessary to take measures which are not needed in the inner rotor type motor. The fan F is made of resin as mentioned above, and the rotor 40 and the rotational shaft 42 rotating together with the fan F are made of metal. In general, a damping rate of vibration of resin is greater than that of vibration of metal. In such a case where the resin-made fan F having a great damping rate is secured to the metal-made rotor 40 and the metal-made rotational shaft 42 each having a small damping rate, the damping rate of the whole of the rotor 40, the rotational shaft 42, and the fan F is greater than each damping rate of the rotor 40 and the rotational shaft 42. Thus, in the compressor A according to the present embodiment, the damping rate of the whole of the rotor 40, the rotational shaft 42, and the fan F rotating together is increased, so the driving noise is reduced. Additionally, the fan F has only to be made of material having a damping rate greater than that of metal. For example, the fan F may be made of an elastic material such as rubber.

FIGS. 5A to 6B are graphs of experimental results illustrating the effects of a reduction in a driving noise by the fan F. FIGS. 5A and 6A illustrate the experiment results of a compressor or a vacuum machine without having the fan F, and FIGS. 5B and 6B show the experiment results of the compressor A having the fan F. FIGS. 5A and 5B respectively illustrate degrees of the vibration damping of the compressor or the vacuum machine without having the fan F, and the compressor A having the fan F in vibrating them. As illustrated in FIGS. 5A and 5B, the vibration of the compressor A having the fan F damps earlier. Also, FIGS. 6A and 6B respectively illustrate degrees of the noise in driving the compressor or the vacuum machine without having the fan F, and the compressor A having the fan F. As illustrated in FIGS. 6A and 6B, the peak value of the noise of the compressor having the fan F is lower than that of the noise, surrounded in a broken line, of the compressor or the vacuum machine without having the fan F. Thus, the experiment results mean an improvement in the vibration damping and a reduction in the noise.

Also, the motor M according to the present embodiment is the outer rotor type motor. The outer rotor type motor has a torque higher than that of an inner rotor type motor, providing that they have the same size. Therefore, the compression state or the vacuum state can be made efficiently.

While the exemplary embodiments of the present invention have been illustrated in detail, the present invention is not limited to the above-mentioned embodiments, and other embodiments, variations and modifications may be made without departing from the scope of the present invention.

The number of the cylinders 10 is not limited to four. The fan F may face the cylinder head 15. Also, the fan F faces the cylinder bodies 12 in the embodiment. However, the blade portion FB or the like may be made large such that the fan F faces the cylinder heads 15. 

What is claimed is:
 1. A compressor comprising: a cylinder; a piston arranged within the cylinder; an outer rotor type motor causing the piston to reciprocate within the cylinder; and a fan fixed to a rotor of the outer rotor type motor and facing at least a part of the cylinder.
 2. The compressor of claim 1, wherein the fan faces a chamber within the cylinder, and a capacity of the chamber increases and decreases in response to reciprocation of the piston.
 3. The compressor of claim 1, wherein a damping rate of vibration of the fan is greater than that of vibration of the rotor.
 4. The compressor of claim 1, wherein the fan is made of resin and the rotor is made of metal.
 5. The compressor of claim 1, wherein the fan is arranged in a radial direction of the rotor.
 6. A vacuum machine comprising: a cylinder; a piston arranged within the cylinder; an outer rotor type motor causing the piston to reciprocate within the cylinder; and a fan fixed to a rotor of the outer rotor type motor and facing at least a part of the cylinder.
 7. The vacuum machine of claim 6, wherein the fan faces a chamber within the cylinder, and a capacity of the chamber increases and decreases in response to reciprocation of the piston.
 8. The vacuum machine of claim 6, wherein a damping rate of vibration of the fan is greater than that of vibration of the rotor.
 9. The vacuum machine of claim 6, wherein the fan is made of resin and the rotor is made of metal.
 10. The vacuum machine of claim 6, wherein the fan is arranged in a radial direction of the rotor. 